Text Diff Checker
Paste the original text on the left and the changed version on the right — the checker highlights exactly which lines were added, removed or left unchanged.
How to use
Paste your two versions and press Compare. Lines that match are shown as-is; removed lines are struck through and marked with “−”, added lines are highlighted and marked with “+”.
Useful for comparing contract or document revisions, checking what changed between two versions of a config file, reviewing edits to an article, or spotting differences between two exports of the same data.
FAQ
How does the diff algorithm work?
It finds the longest common subsequence of lines shared between both texts, then reports everything outside that sequence as added or removed — the same principle used by `diff` and Git, applied line by line rather than character by character.
Does it compare word by word or line by line?
Line by line. If a single word changes in a long paragraph, the whole line is marked as removed and its replacement as added, rather than highlighting just the changed word.
Is there a size limit?
Yes, 2,000 lines per side. The comparison algorithm's cost grows with the product of both lengths, so very large documents are better split into sections before comparing.
Is my text uploaded anywhere?
No — the comparison runs entirely in JavaScript in your browser. Neither text is sent to a server, which makes this safe for confidential documents and unpublished drafts.